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  1. AU="Andreas?Schumann"
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  1. Article ; Online: A statistics-based automated flood event separation

    Svenja Fischer / Andreas Schumann / Philipp Bühler

    Journal of Hydrology X, Vol 10, Iss , Pp 100070- (2021)

    2021  

    Abstract: The classification of characteristics of flood events, like peak, volume, duration and baseflow components is essential for many hydrological applications such as multivariate flood statistics, the validation of rainfall-runoff models and comparative ... ...

    Abstract The classification of characteristics of flood events, like peak, volume, duration and baseflow components is essential for many hydrological applications such as multivariate flood statistics, the validation of rainfall-runoff models and comparative hydrology in general. The basis for estimations of these characteristics is formed by flood event separation. It requires an indicator for the time when a flood peak occurs as well as the definition of the beginning and end of a flood event and a subdivision of the total volume into direct and baseflow components. However, the variable nature of runoff and the multiple processes and impacts that determine rainfall-runoff relationships make a separation difficult, especially an automation of it. We propose a new statistics-based flood event separation that was developed to analyse long series of daily discharges automatically to obtain flood events for flood statistics. Moreover, the related flood-inducing precipitation is identified, allowing the estimation of the flood-inducing rainfall and the runoff coefficient. With an additional tool to manually check the separation results easily and quickly, expert knowledge can be included without much effort. The algorithm was applied to seven basins in Germany, covering alpine, mountainous and flatland catchments with different runoff processes. In a sensitivity analysis, the impact of chosen parameters was evaluated. The results show that the algorithm delivers reasonable results for all catchments and only needs manual adjustment for long timeslots with increasing or high baseflow. It reliably separates flood events only instead of all runoff events and the estimated beginning and end of an event was shifted in mean by less than one day compared to manual separation.
    Keywords Flood event separation ; Runoff variation ; Automation ; Environmental engineering ; TA170-171 ; Environmental sciences ; GE1-350
    Subject code 550
    Language English
    Publishing date 2021-01-01T00:00:00Z
    Publisher Elsevier
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: GEOSITES AS A POTENTIAL FOR THE DEVELOPMENT OF TOURISM – OVERVIEW OF RELEVANT SITES IN ESWATINI (FORMERLY SWAZILAND)

    Thomas SCHLÜTER / Andreas SCHUMANN

    Geo Journal of Tourism and Geosites, Vol 22, Iss 2, Pp 535-

    2018  Volume 547

    Abstract: Despite being one of the smallest countries in Africa, the Kingdom of Eswatini (formerly Swaziland) is characterized by many locations, which are due to their geoscientific significance to be termed as geosites, and which are here in an overview ... ...

    Abstract Despite being one of the smallest countries in Africa, the Kingdom of Eswatini (formerly Swaziland) is characterized by many locations, which are due to their geoscientific significance to be termed as geosites, and which are here in an overview presented and briefly explained. Each of them can be assigned to a specific scientific approach, e.g. as a landscape, a geological, a geomorphologic, an archaeological (prehistoric) or a mining heritage site. Eswatini yields remarkable landscapes like the Mahamba Gorge and the Sibebe Monolith, it exhibits worldwide one of the largest in granite formed caves (Gobholo), and possibly the oldest dated rocks in Africa (Piggs Peak gneisses), as well as beautiful and scientifically relevant rock painting sites (Nsangwini, Sandlane and Hholoshini) and three abandoned mines in the Barberton Greenstone Belt (Forbes, Ngwenya and Bulembu). The latter have contributed largely to the infrastructural development of the country. The geotouristic value of the respective sites is evaluated and commented, and it is assumed that in future these and other, here not yet mentioned geosites, may contribute to income generating processes for the country and the local communities.
    Keywords Eswatini (Swaziland) ; geoheritage ; geosites ; geology ; geomorphology ; archaeology ; mining ; geo-tourism ; Geography. Anthropology. Recreation ; G ; Geography (General) ; G1-922
    Subject code 930
    Language English
    Publishing date 2018-07-01T00:00:00Z
    Publisher Editura Universităţii din Oradea
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article: A distribution-free ordinal classification of floods based on moments

    Fischer, Svenja / Andreas Schumann

    Hydrological sciences journal. 2018 Aug. 18, v. 63, no. 11

    2018  

    Abstract: Classification of floods is often based on return periods of their peaks estimated from probability distributions and hence depends on assumptions. The choice of an appropriate distribution function and parameter estimation are often connected with high ... ...

    Abstract Classification of floods is often based on return periods of their peaks estimated from probability distributions and hence depends on assumptions. The choice of an appropriate distribution function and parameter estimation are often connected with high uncertainties. In addition, limited length of data series and the stochastic characteristic of the occurrence of extreme events add further uncertainty. Here, a distribution-free classification approach is proposed based on statistical moments. By using robust estimators the sampling effects are reduced and time series of different lengths can be analysed together. With a developed optimization procedure, locally and regionally consistent flood categories can be defined. In application, it is shown that the resulting flood categories can be used to assess the spatial extent of extreme floods and their coincidences. Moreover, groups of gauges, where simultaneous events belong to the same classes, are indicators for homogeneous groups of gauges in regionalization.
    Keywords floods ; gauges ; probability distribution ; time series analysis ; uncertainty
    Language English
    Dates of publication 2018-0818
    Size p. 1605-1618.
    Publishing place Taylor & Francis
    Document type Article
    ISSN 2150-3435
    DOI 10.1080/02626667.2018.1525614
    Database NAL-Catalogue (AGRICOLA)

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  4. Article: Ordinal pattern dependence between hydrological time series

    Fischer, Svenja / Alexander Schnurr / Andreas Schumann

    Journal of hydrology. 2017 May, v. 548

    2017  

    Abstract: Ordinal patterns provide a method to measure dependencies between time series. In contrast to classical correlation measures like the Pearson correlation coefficient they are able to measure not only linear correlation but also non-linear correlation ... ...

    Abstract Ordinal patterns provide a method to measure dependencies between time series. In contrast to classical correlation measures like the Pearson correlation coefficient they are able to measure not only linear correlation but also non-linear correlation even in the presence of non-stationarity. Hence, they are a noteworthy alternative to the classical approaches when considering discharge series. Discharge series naturally show a high variation as well as single extraordinary extreme events and, caused by anthropogenic and climatic impacts, non-stationary behaviour. Here, the method of ordinal patterns is used to compare pairwise discharge series derived from macro- and mesoscale catchments in Germany. Differences of coincident groups were detected for winter and summer annual maxima. Hydrological series, which are mainly driven by annual climatic conditions (yearly discharges and low water discharges) showed other and in some cases surprising interdependencies between macroscale catchments. Anthropogenic impacts as the construction of a reservoir or different flood conditions caused by urbanization could be detected.
    Keywords anthropogenic activities ; climatic factors ; correlation ; flooded conditions ; hydrologic data ; summer ; time series analysis ; urbanization ; watersheds ; winter ; Germany
    Language English
    Dates of publication 2017-05
    Size p. 536-551.
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 1473173-3
    ISSN 0022-1694
    ISSN 0022-1694
    DOI 10.1016/j.jhydrol.2017.03.029
    Database NAL-Catalogue (AGRICOLA)

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  5. Article: Characterisation of seasonal flood types according to timescales in mixed probability distributions

    Fischer, Svenja / Andreas Schumann / Markus Schulte

    Journal of hydrology. 2016 Aug., v. 539

    2016  

    Abstract: When flood statistics are based on annual maximum series (AMS), the sample often contains flood peaks, which differ in their genesis. If the ratios among event types change over the range of observations, the extrapolation of a probability distribution ... ...

    Abstract When flood statistics are based on annual maximum series (AMS), the sample often contains flood peaks, which differ in their genesis. If the ratios among event types change over the range of observations, the extrapolation of a probability distribution function (pdf) can be dominated by a majority of events that belong to a certain flood type. If this type is not typical for extraordinarily large extremes, such an extrapolation of the pdf is misleading. To avoid this breach of the assumption of homogeneity, seasonal models were developed that differ between winter and summer floods. We show that a distinction between summer and winter floods is not always sufficient if seasonal series include events with different geneses. Here, we differentiate floods by their timescales into groups of long and short events. A statistical method for such a distinction of events is presented. To demonstrate their applicability, timescales for winter and summer floods in a German river basin were estimated. It is shown that summer floods can be separated into two main groups, but in our study region, the sample of winter floods consists of at least three different flood types. The pdfs of the two groups of summer floods are combined via a new mixing model. This model considers that information about parallel events that uses their maximum values only is incomplete because some of the realisations are overlaid. A statistical method resulting in an amendment of statistical parameters is proposed. The application in a German case study demonstrates the advantages of the new model, with specific emphasis on flood types.
    Keywords case studies ; floods ; probability distribution ; statistical models ; summer ; watersheds ; winter
    Language English
    Dates of publication 2016-08
    Size p. 38-56.
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 1473173-3
    ISSN 0022-1694
    ISSN 0022-1694
    DOI 10.1016/j.jhydrol.2016.05.005
    Database NAL-Catalogue (AGRICOLA)

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  6. Book ; Online: Integrative Nutzung des technischen Hochwasserrückhalts in Poldern und Talsperren am Beispiel des Flussgebiets der Unstrut

    Universität Bochum, Lehrstuhl für Hydrologie, Wasserwirtschaft und Umwelttechnik / Andreas Schumann

    Verbundvorhaben ; Abschlussbericht ; Laufzeit des Vorhabens: 01.02.2005 bis 31.05.2008

    2008  

    Publishing country de
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Book ; Online: Entwicklung integrativer Lösungen für das operationelle Hochwassermanagement am Beispiel der Mulde

    Universität Bochum, Lehrstuhl für Hydrologie, Wasserwirtschaft und Umwelttechnik / Andreas Schumann

    Verbundvorhaben ; Abschlussbericht

    2008  

    Publishing country de
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article ; Online: Entwicklung und Testung eines stochastischen Niederschlagsgenerators zur Erstellung hydrologischer Belastungsszenarien

    Yeshewatesfa Hundecha / Markus Pahlow / Bastian Klein / Andreas Schumann

    Forum für Hydrologie und Wasserbewirtschaftung

    2008  

    Publishing country de
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  9. Article ; Online: Using Trace Metals, Peroxide, Acid and Iodine Values to Characterize Oils Bleached Using Clays from Central and Eastern Uganda

    Is’harq-Zubair Mukasa-Tebandeke / Pancras John Mukasa Ssebuwufu / Steven A. Nyanzi / Andreas Schumann / George W. Nyakairu / Festo Lugolobi

    American Journal of Analytical Chemistry , Vol 05, Iss 17, Pp 1302-

    2014  Volume 1312

    Abstract: Bleaching of edible oils is known to alter the composition of oils as it removes impurities and certain food nutrients. The characteristics of bleached oil are strongly related to type bleaching medium, temperature at which bleaching is done and other ... ...

    Abstract Bleaching of edible oils is known to alter the composition of oils as it removes impurities and certain food nutrients. The characteristics of bleached oil are strongly related to type bleaching medium, temperature at which bleaching is done and other factors. In this study, we compare peroxide, free fatty acid, acid and iodine values, copper and iron content of bleached and crude oils to establish the characteristics of edible oils bleached using smectite and kaolinite-rich clays. Oil industries spend large sums of money purchasing bleaching earths yet no country lacks natural clays which can be developed to bleach oils. In Uganda alone more than US$ 700,000 is spent every month yet many clay deposits are unexploited. In this study, we have documented trace metal composition, peroxide values, acid values, iodine values and free fatty acid content of bleached and unbleached cotton-seed and sunflower seed oils. The bleached oils were found to be fit for human use. Clays are either kaolinites or smectites, but the clays used to bleach edible oils are montmorillonites or bentonites. The decrease in content of iron in the bleached oils was highest for all oils bleached. The content of copper showed the smallest change. The content of copper in cotton oils decreased from 0.5 ppm to 0.15 ppm using Kajansi clay leached in 20% acid yet when Chelel clay leached under similar conditions was used decrease was from 0.5 to 0.1 ppm. The content of iron in sunflower oils bleached using Kajansi clay leached in 20% acid decreased from 1.6 to 0.2 ppm yet that bleached with Chelel clay under similar conditions decreased to 0.1 ppm. The acid values showed that the acidity in sunflower oils is largely due to oleic acid as the average value for acids is in the range close to oleic acid, cotton-seed oil corresponded to linoleic acid. The levels of free fatty acid were found to lie in range from 3.8 - 3.2 for all clays used showing no significant rise. The peroxide values of bleached oils lay between 1.2 and 0.8.
    Keywords Bleached Oil ; Clays ; Trace Metals ; Peroxide ; Iodine ; Analytical chemistry ; QD71-142 ; Chemistry ; QD1-999 ; Science ; Q
    Subject code 571
    Language English
    Publishing date 2014-12-01T00:00:00Z
    Publisher Scientific Research Publishing
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  10. Article ; Online: Causative classification of river flood events

    Larisa?Tarasova / Ralf?Merz / Andrea?Kiss / Stefano?Basso / G?nter?Bl?schl / B.?Merz / Alberto?Viglione / Stefan?Pl?tner / Bj?rn?Guse / Andreas?Schumann / Svenja?Fischer / Bodo?Ahrens / Faizan?Anwar / Andr?s?B?rdossy / Philipp?B?hler / Uwe?Haberlandt / H.?Kreibich / Amelie?Krug / David?Lun /
    Hannes?M?ller?Thomy / Ross?Pidoto / Cristina?Primo / Jochen?Seidel / S.?Vorogushyn / Luzie?Wietzke

    Wiley Interdisciplinary Reviews: Water

    2019  

    Abstract: A wide variety of processes controls the time of occurrence, duration, extent, and severity of river floods. Classifying flood events by their causative processes may assist in enhancing the accuracy of local and regional flood frequency estimates and ... ...

    Abstract A wide variety of processes controls the time of occurrence, duration, extent, and severity of river floods. Classifying flood events by their causative processes may assist in enhancing the accuracy of local and regional flood frequency estimates and support the detection and interpretation of any changes in flood occurrence and magnitudes. This paper provides a critical review of existing causative classifications of instrumental and preinstrumental series of flood events, discusses their validity and applications, and identifies opportunities for moving toward more comprehensive approaches. So far no unified definition of causative mechanisms of flood events exists. Existing frameworks for classification of instrumental and preinstrumental series of flood events adopt different perspectives: hydroclimatic (large?scale circulation patterns and atmospheric state at the time of the event), hydrological (catchment scale precipitation patterns and antecedent catchment state), and hydrograph?based (indirectly considering generating mechanisms through their effects on hydrograph characteristics). All of these approaches intend to capture the flood generating mechanisms and are useful for characterizing the flood processes at various spatial and temporal scales. However, uncertainty analyses with respect to indicators, classification methods, and data to assess the robustness of the classification are rarely performed which limits the transferability across different geographic regions. It is argued that more rigorous testing is needed. There are opportunities for extending classification methods to include indicators of space?time dynamics of rainfall, antecedent wetness, and routing effects, which will make the classification schemes even more useful for understanding and estimating floods.
    Subject code 550
    Language English
    Publishing country de
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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